Cam clamp



Aug. 9, 1960 s. J. ROUNDS ETAL CAM CLAMP 2 Sheets-Sheet 1 Filed Oct. 17, 1957 /q //VVENTOR5. I J 3 ATTORNEY,

A ug 9, 1960 v s.J, ROUNDS ETAL 2,948,509

CAM CLAMP Filed Oct. 17, 1957 2 Sheets-Sheet 2 2,948,509 CAM CLAMP Samuel J. Rounds and JamesG. Rounds, both Henderson, N.Y.

' Filed Oct. 17, 1951, Ser. No. 690,785 1 Claims 01. 254-77 This invention relates to retractable tension cam clamps for drawing parts toward one another quickly and easily, and locking the parts under tension.

The invention in its simplest form comprises a pair of elements having tension attachment means which may' be moved lengthwise relative to one another by an over-center cam. The invention is directedtoward providing a simple rugged and effective structure, of. low cost, for applying tension between parts whereby to hold parts in'place.

- The above and other novel features of the invention will appear more fully hereinafter from the following detailed description when taken in conjunction with the accompanying drawings. thefld'raWings are employed for purposes of illustration only and are not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In thedrawings, wherein like reference characters indicate like parts:

. Figure l is a plan view of the cam clamp extended; Figure 2 is a plan view from the reverse side of the clamp fully retracted; i

Figure 3 is a side elevational view of' the clamp retracted;

Figure 4 is a side elevational view of the clamp extended;

Figure 5 is a sectional view of the clamp taken on the line 5-5 of Figure 1;

Figure 6 is a sectional view taken on the line 6-6 of Figure 2;

Figure 7 is an alternate construction similar to Figure 6;

Figure 8 is a fragmentary plan view showing an alternate construction;

Figure 9 is a sectional view taken on the line 9-9 of Figure 8; and

Figure 10 is a fragmentary schematic view of the clamp applied to one end of a motor vehicle roof rail.

In Figure 1 there are shown overlapping tension members and 22 which are adapted to slide lengthwise with respect to each other through operation of a cam member 24 pivoted upon and at one end of member 20. The member 20 is provided at its lower end with a suitable hook 26 or other attachment means, and has extending along its length a longitudinal rectangular slot 28. The member 22 is provided with a reverse bent tongue portion 30 somewhat narrower than the width of the body portion of such member, such reverse bent portion being of a width so as to pass through the slot 28 and form a guide in the slot, as well as a bearing support arm 32. A stub shaft 34 extends between the arm 32 and the lower end 23 of the member 22. Located upon the shaft 34 and between the arm 32 and the main portion of the member 22 is a free roller 36 for engaging cam member 24.

The upper end of the member 22 is provided with an extension 38 or other attachment means, the lower end It is expressly understoodthat' Patented Aug. 9, 1960 ICC cam 24 has a circular cam surface 56 and an operating handle 58. The center of the circular cam surface is disposed on a line 60 extending parallel with the handle 58 and through the center of the stud S4. The cam is adapted to engage the roller 36 carried on the stub shaft at the lower end of the member 22. It will be seen that the portion of the cam indicated at 62 provides a suitable over-the-center contact with the roller 36 when the cam is in the position shown in Figure 2, that is, with the tension members 20 and 22 retracted.

It will be seen that the tension member, for example,

when one is appliedto each end of a roof rail 70, mounted on the roof 72 of a'motor vehicle, may be hooked to the rain trough 74, at its lower end, and

provided with an 8 link 76 engaging the end of a rail 70 at its upper end. By suitable adjustment of'the shank 46 the properlength of the cam clamp may be established, after which the cam member 24 may be rotated in the direction shown by the arrow A in Figure 2 to retract the members 20 and 22 and draw the roof rails tight upon the top of the vehicle, the opera-1 tion compressing the rubber feet 78 and securing the rails rigidly to the top. As soon as the over-center portion 62 of the cam engages the roller 36, the clamp becomes locked in retracted position, by the over-center efiect.

While the device thus described is of suitable weight and strength for securing roof rails as an example, it will be understood that the cam clamp may be made in various sizes to handle various loads. Should it be desirable to introduce anti-friction sliding surfaces so as to render the retraction of the clamp relatively free of friction, suitable rollers or balls may be provided at various points. As shown in Figure 7 a separate roller 80 may be positioned on the pin 34, such roller being of sufiicient diameter to roll against an inside surface of the slot 28 to react against the side thrust exerted by the cam upon rotation to effect retraction. A second roller 84 rides upon the edge of the cam 24 to provide low friction at that point as before. The main member 20 may be channeled as shown in Figures 8 and 9 as at 88 to form a guide way for the member 22. If desired, the channels may be provided with pockets retaining anti-friction balls such as 90 which project sufliciently from the inside surfaces of the flanges to provide a rolling contact with the side edges of the member 22.

From the foregoing description it can be seen that the tension device may be used in a multiplicity of situations wherein it is necessary to draw parts together easily and quickly, and thereafter hold them in that position until such time as it is desired to release the tension.

Although a single embodiment of the invention with slight variations has been illustrated and described, it is to be understood that the invention is not limited thereto. As various changes in the construction and arrangement may be made without departing from the spirit of the invention, as will be apparent to those skilled in the art, reference will be had to the appended claims for a definition of the limits of the invention.

The member 20 above the upper end of the slot 28 is provided with an aperture 52 through whichextends a heavy stud 54, the stud forming a pivot for the cam member 24 and acting as a guide pin vridingin the elongated slot 25 of the upper member 22. The

3 What is claimed is: 1. A cam clamp comprising a pair of elongated members, guide means comprising an elongated slot in each of said members, and a guide on one end of each of said 7 members extending into the slot of the other member, acam. pivoted upon the guide of one of said members, a cam follower carried by the other of said members ad'- jacent' the guide end thereof, said cam engaging said follower, and being adapted on rotation thereof relative to one of said members, to effect relative longitudinal movement between the members.

2. A cam clamp comprising a pair of elongated members, guide means comprising an elongated slot in each of said members, and a guide on one end of each of said members extending into the slot of the other member, a cam pivoted upon the guide of one of said members, a cam follower carried by the guide of the other of said members, said cam engaging said follower, and being adapted, 0n rotation thereof relative to said members, to effect relative longitudinal movement between the members to draw the other ends of said members toward each other.

3. A cam clamp comprising a pair of elongated members, each member having an elongated slot, and each member having a guide at one end projecting into the slot of the other member, a cam pivoted to one of said members near the guide thereof, a cam follower carried by the other of said members adjacent the guide end thereof, said cam engaging said follower, and being adapted on rotation thereof relative to one of said mem bers, to effect relative longitudinal movement between themembers, and tension attachment means aflixed to the opposite ends of each of said members.

4. A, cam clamp comprising a pair of elongated members, each having an elongated slot, and a guide on one end of each of said members extending into the slot of the other member, a cam pivoted upon the guide of one of said members, a cam follower carried by the guide of said other member, said cam engaging said follower, and being adapted on rotation thereof relative to one of said members, to draw the other ends of said members toward each other, and tension attachment means on theother end of each of said members.

5. A cam clamp comprising a pair of elongated members, each having an elongated guide slot, each of said members at one end having guide means projecting into the slot of the other member, a cam pivotally mounted on one of said members adjacent the guide means thereof, and cam follower means on the other member disposed adjacent the guide means thereof, said cam follower means and said cam coacting together to effect relative longitudinal movement between said members upon rotation of said cam.

6. A cam clamp comprising a pair of elongated members, each having an elongated slot, a stud extending through one end of one of said members beyond the slot, and having one end extending into the slot of the other member, a cam having an eccentric over center cam contour edge terminating in a generally radially extending Operating lever pivoted on the other end'of said stud, a reverse bent portion formed on one end of the other member, said portion extending through the slot of said one member, a pin extending between the end of the other member and the end of said reverse bent portion and through the slot of said one member, roller means journalled on said pin adapted to roll on the opposite sides of the slot of said one member, and adapted to engage the cam contour edge, said cam being adapted on rotation to draw the other ends of said members toward each other, said members having tension attachment means at each of their other ends.

7. A cam clamp as set forth in claim 6, wherein the one member is of channel section at the stud end, and the flanges of said channel section have anti-friction means mounted on their inside faces in engagement with the side edges of the other member.

References Cited in the file of this patent UNITED STATES PATENTS 758,942 Taylor et al.. May 3, 1904 1,072,099 Neergaard Sept. 2, 1913 2,739,748 Hoover Mar. 27, 1956 

